Separation of ketoses from mixtures



Patented Jan. 24, 1933 UNITED STATES PATENT? oFFica EDWARD L HELWIG, F BRISTOL, PENNSYLVANIA, ASSIGNOR T0 36H!!! & HAAS COMPANY, OF PHILADELPHIA, PENNSYLVANIA snranarron or xnrosas rnom mrxronus lo Drawing.

This application relates to an electrolytic process for the separation of ketoses from mixtures of aldoses and ketoses, and is a continuation in part of U. S. Serial No. 515,648,

February 13th, 1931.

The separation of mixtures of aldoses and ketos'es has always been a diflicult problem from a technical standpoint, due to the similarity of the properties of these sugars. A

13 number of recrystallizations have been necessary in order to get a clean separation. The new method which 1 herein describe has overcome this cumbersome separation of these two classes of sugars. The electric current 15 oxidizes the aldoses almost quantitatively to their corresponding monocarboxylic acids without affecting the ketoses. (See my copending application #427,065 filed February 8th, 1930, Electrolytic oxidation of aldoses 29 etc) The monocarboxylic acids, being entirely difi'erent from the unoxidized ketosesugars, are easily separated. It is true that this oxidation can also be accomplished with a" hypobromites or hypoiodites, but it is then pensive reagent, and the recovery of the ketose is rendered diiiicult by the large amount of bromide or iodide produced in the reaction. The oxidation can also be accomplished with hypochlorite to which iodides or bromides have been added(U. 5. Patents Nos. 1,648,368 and 1,70S,755Arthur Stoll and Walter Kussmahl). This method, however, yields the desired products mixed with great quantities of alkali or alkaline earth salts,

which not onl render the isolationtof the ketose diiiicult hut greatly complicate the recovery of the expensive bromide or iodine. The electrolytic process, herein described, si-

multaneously produces the monocarhoxylic acids of the aldoses in such a form that they are easily recoverable, and yields the ketose associate with a small amount of bromide or iodide, from which it can be readily separated. After the ketose is removed from the solution, the residual liquor is evaporated, ignited and the expensive halogen is recovered almost quantitatively by leaching the ash.

The source of the sugar mixturesis imma- J necessary to use a large quantity of an ex Application filed March 30, 1931. Serial No. 526,569.

terial for the purposes of this invention. Naturally occurring mixtures such as honey, plant juices and the like can be used as can also inverted sucrose and any synthetically pre ared mixture. The example below inclu es as a preliminary step the preparation of an invert sugar but it should be understood that the invention is not confined to a sugar mixture thus prepared. A soluble bromide or iodide is added to the sugar mixture and a substance capable of neutralizing the mono carboxylic acid as it is formed, is added. ll have found that the hydroxides, carbonates and bicarbonates of the alkalies and alkaline earth metals are satisfactory for their purpose. It is then electrolyzed, using insoluble anodes. No diaphragm is required, and the cathode may be of iron, copper, lead, aluminum, nickel or almost any of the common metals. Enough agitation is necessary to m keep some of the base in suspension. When suihcient current has passed through the cell 7 to oxidize all the aldose present, electrolysis I is stopped, excess base is removed by neutralization, the solution is concentrated, if necessary, and the sparingly soluble salt of the monocarboxylic acid crystallizes out.

The following examples will serve to illustrate the nature of my invention, but it is not limited to these special cases, nor as to temperature, concentration, sequence of operations or other conditions.

Ezmmple 1. ams of sucrose were dis solved in 170 cc. 0 water; 10 grams of sulphuric acid in 50 cc. of water were added and heated to C. for 30 minutes. lit was then neutralized with lime, filtered and washed. Analysis showed that the filtrate contains 54 grams of invert sugar. To this were added 2 grams of potassium iodide and 5.5 grams of lime. This electrolyte was placed in an iron cup, which s rved as a cathode, and a rotating graphite anode was placed in the center of it.

It was electrolyzed at a temperature of 10 C. with a current density of 15 amperes per square foot. When 7.9 ampere hours had passed through the cell, electrolysis was stopped. The excess lime was neutralized with sulphuric acid, and the electrolyte was evaporatedat cc. and allowed to stand for no grams of invert sugar.

- 1. Inthe process for the forty-eight hours. A dense precipitate of calcium g'luconate was formed, which was centrifuged off and washed. The filtrate and washin s were concentrated to 60 cc., and this was added slowing to 6 grams of lime in 40 cc. of water, the temperature being kept at 2 C. during the addition. The sparingly soluble calcium fructosate crystallized out. This was filtered OE and washed. It was then suspended in water and decomposed with carbon dioxide. The calcium carbonate was filtered off, and the filtrate concentrated and precipitated with alcohol, the fructose be-. ing removed by filtration. The filtrate was then evaporated for recovery of-the alcohol. The filtrate from the calcium fructosate was evaporated, ignited and leached with water for recovery of the sodium bromide.

Ewwmple Q.60 rams of sucrose were dissolved in 170 cc. 0? water; 10 grams of sulhuric acid in cc. of water were added and eated to 70 C. for 30 minutes. It was then neutralized with lime, filtered and washed. Analysis showed that the filtrate contained 54 To this were added 2 grams of potassium iodide and 6.5 grams of calcium carbonate. placed in an iron cup, which served as a cathode, and a rotating graphite anode was placed in the center of it. It was electrolyzed at a temperature of 10 C. with a current density of 15 amperes per square foot. When 7 .9 ampere hours had passed through the cell, electrolysis was stopped. The electrolyte was evaporated to 100 cc. and allowed to stand for forty-eight hours. A dense precipitate of calcium gluconate was formed, which was centrifuged off and washed. The filtrate and washings were concentrated to cc., and this was added slowly to 6 grams of lime in 40 cc. of water, the temperature being kept at 2 C. during the addition. The sparingly soluble calcium fructosate crystallized out. This was filtered ofiand washed. It was then suspended in water and decomposed with carbon dioxide. The calcium carbonate was filtered oif, and the filtrate concentrated and precipitated with alcohol, the fructosebeing removed by filtration. The filtrate was then evaporated for recovery of the alcohol. The filtrate from the calcium fructosate was evaporated, ignited and leached with water for recovery of the sodium bromide. It will be recognized by one versed in the art that wide variations may be made in the above 8 ifications within the irit of the invention, the sec of which is 'mited only. by the claims whic follow.

What I claim as new is:

separation of ketoses from mixtures of aldoses and ketoses thostep which comprises electrolyzing the mixture in the presence'of a substance capable of neutralizing the monocarboxylic acid formed and in the presence of a. soluble salt This electrolyte was containing a halogen of higher molecular weight than chlorine.

2. Process as in claim 1 in whichthe rocess is carried out with an insoluble anod ei.

3. In the process of separating ketoses from mixtures of aldoses and ketoses the step of electrolyzing the mixture with an insoluble anode in the presence of a substance capable of neutralizing the monocarboxylic acid formed and in the resence of a salt containing a halogen of higher molecular weight than chlorine.

4. A step as described in claim 3 in which v lime is the neutralizing substance.

5. A step as described in claim 3 in which calcium carbonate is the neutralizing substance.

. 6. A step as described in claim 3'in which the neutralizing substance is one of the group consisting of hydroxides, carbonates and bicarbonates of the alkalies and alkaline earth metals.

7. In the process for the separation of fructose from the constituents of invert sugar the step comprising electrolyzing the mixture in the presence of one of the group consisting of hydroxides, carbonates and bicarbonates of the alkalies and alkaline earth metals and in the presence of a salt containing a halogen of higherhiolecular weight than chlorine.

8. The process for the separation of ketose H ing lime and filtering off the calcium salt thus formed, suspending it in water and treating it with carbon dioxide for liberation of the ketose and then working it up by known methods.

. 9. In the process for the simultaneous 1S0- lation of ketoses and oxidation of aldoses,

the step which comprises electrolyzing the mixture in the presence of one of the group consisting of hydroxides, carbonates, andbicarbonates of the alkalies and alkali earth metals and in the presence of a salt containing a halogen of higher molecular weight than chlorine.

10. In the proces for the simultaneous isolation of fructose and oxidation of glucose to gluconic acid, the step which comprises In testimony whereof I aflix my EDWARD L. HELWIG.

electrolyzing the mixture in the presence of .1

ydroxides, 

